FIG. 1 shows a typical surgical robot for performing robotic surgery. The surgical robot 101 comprises a robotic arm 103 attached at one of its ends to a surgical instrument 105. The surgical instrument is operable to pass into a patient for performing surgery. The robotic arm comprises one or more joints 107 about which the arm can be articulated to control the movement and/or position of the surgical instrument. FIG. 1 also shows a surgical robotic drape 109 which shrouds the robotic arm to provide a sterile boundary between the surgical instrument (which must be sterile) and the robotic arm (which is not necessarily sterile).
The robotic drape is an effective low-cost solution for maintaining a sterile surgical environment which negates the need for sterilising the robotic arm. The surgical instrument (which is typically of substantially lower cost than the robotic arm) can be made to be disposable after each use to ensure adequate surgical hygienic standards are maintained, or can be sterilized (e.g. in an autoclave) after use. However, a problem with the drape is that by enclosing the robotic arm it may cause the arm (in particular the motors driving articulation about the joints) to overheat. This problem may be exacerbated by the fact that the motors used within robotic arms are often designed to be relatively small so as to reduce the weight and size of the arm, which means that during operation the motors are operating at a relatively high rotation speed and therefore generate large amounts of heat.
One approach to provide cooling is to integrate ducts within the robotic arm that channel cooling fluid, for example cool air or possibly a liquid coolant, into and out of the robotic arm. However, it is often advantageous and desirable for robotic arms to be made to minimise bulk and weight. For example, one advantage of a smaller, more lightweight robotic arm from the viewpoint of a surgeon is that it may improve the usability and manoeuvrability of the surgical robot; from the point of view of the patient, a smaller robotic arm may appear less intrusive, or intimidating. Consequently, space within the robotic arm is often at a premium, meaning it may be impractical or difficult to install ducts that both channel fluid to the arm and ducts that channel fluid away from the arm.
There is therefore a need for an improved way of cooling a surgical robotic arm.